• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.241-258
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• 2019

The aim of this study was to analyze the factors that affect the habitat of fishes and amphibians in a mountain stream that is part of an experimental forest at Kongju National University, Gongju, Chungcheongnam, Korea, and examine the differences in the presence of fishes and amphibians in the stream before and after construction of an erosion control dam. The results showed that the factors that affect the presence of fishes are pH, electrical conductivity (EC), dissolved oxygen (DO), flow velocity, and step-pool number, and that the factors that affect the presence of amphibians are monthly rainfall, pH, EC, DO, and crown density. Of these factors, pH, EC, flow velocity, and monthly rainfall were significantly different before and after dam construction; however, the differences among the other three factors from dam construction, except EC, might not have been enough to affect the presence of fishes and amphibians. Our results suggest that the difference in the frequency of fishes and amphibians surveyed before and after dam construction in the upper and lower stream sections were not statistically significant. One exception to this was the presence of amphibians in the lower stream section during and after dam construction, which could have been the result of a large amount of sediment produced by excavation that led to high EC.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.171-179
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• 2022

The present study investigated the survival rate, respiration rate, plasma stress index, and histological changes according to exposure time of cultured red seabream (Pagrus major) and olive flounder (Paralichthys olivaceus) exposed to Cochlodinium polykrikoides red tide. Fish cultured in natural seawater were used as the control group. Cochlodinium polykrikoides density was set to 5,500±200 cells·ml^-1 in the experimental groups. All red seabreams died within 1 hour of exposure to red tide, whereas all olive flounders died within 5 hours of exposure. Analysis of physiological response revealed that in red seabream, plasma glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), catalase (CAT), and glutathione peroxidase (GPx) concentrations were increased; plasma glucose and superoxide dismutase (SOD) concentration were decreased. Meanwhile, in olive flounders, plasma cortisol, GOT, and GPT concentrations were increased; plasma glucose concentrations were increased during the first hour of exposure, followed by decrease after 5 hours; and plasma SOD, CAT, and GPx concentrations decreased during the first hour of exposure. Histological analysis revealed structural damage to the gills of both red seabream and olive flounder. In conclusion, the exposure of red seabream and olive flounder to Cochlodinium polykrikoides red tide at the density of 5,500 cells·ml^-1 induces oxidative stress, which activates antioxidant defense mechanisms, ultimately leading to liver and gill damage.

• Journal of the Korean Home Economics Association
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• v.11 no.4
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• pp.374-387
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• 1973

This work was carried out to investigate the changes of chemical and physical properties of frying oil, when it was used many times continuously without adding new oil. Four kinds of frying oil (soybean oil, rapeseed oil, shortening and crude lard) and slices of potato and Aji (kind of fish) were used in the experiment under the condition of home cooking. Obtained results were as in the followings. 1. Acid values and peroxide values of each frying oil were under the safety level (A. V = 1.5, Po. V = 50) except crude lard, when frying works were continuously repeated five times for 50 days. 2. Changes of saponification values of each frying oil showed a decreasing tendency except the crude lard. But in cases, stickiness or clothing of oil were not seen in frying even at the five times frying. 3. Changes of optical density of each frying oil showed a decreasing tendency in all cases, according to the times of frying, especially at the first time frying. 4. Maximum heights of the shamp of each frying oil and their shampholding activites when heated, were slowly increased according to the times of frying. 5. Without concerning the cooking condition (kinds of oil, cooking material and repeating times of frying) decrement of oil in once frying was almost exactly 20g per 150g. 6. Decrements of cooking material in all cases of frying showed almost constant values, potato to be 40% and Aji 20%. 7. Differences of smoke point between new and old oil (frying repeated 5 times) showed also almost constant values. Liquid oil (soybean oil and rapeseed oil) showed number (6-$10^{\circ}C$), on the contrally solid oil (shortening and crude lard) a high number (10-$25^{\circ}C$). 8. Results of public tastic for the frying products were almost good even in that of a low five times frying, but the products, of third time frying with crude lard were expressed as disagreeable.

• Applied Microscopy
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• v.30 no.3
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• pp.303-310
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• 2000

Ultrastructures on the integumentary epidermis of the marbled sole, Limanda yokahamae, were examined by means of the light and transmission electron microscope. Epidermal layer consists of supporting cells, unicellular glands and accessory cells. The supporting cells were classified into superficial cell, intermediated cell and basal cell. The cytoplasm of supporting cells is divided into cortex and medullar part. In the cortex and medullar part, microfilaments and cell organelles are well developed, respectively. Gland cells are present in the superficial and middle epidermis. The cytoplasm of mucous cell reacted to blue in AB-PAS (pH 2.5). Club cell has a roundish central vacuole and well-developed microfilaments in the cytoplasm. Granular cells are occurs in the middle and basal epidermis , and the cytoplasm is occupied with membrane-bounded granules of electron dense. Chloride cells are present in the superficial epidermis , and the cytoplasm is occupied with tubular mitochondria. Three types of pigment cells can be distinguished by electron density of cytoplasmic inclusions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.381-386
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• 2010

We have cultured the bluefin tuna in Yokjido, Tongyeong with floating cage which was vulnerable to harmful dinoflagellate, Cochiodinium polykrikoides. This study inspected a vertical migration of phytoplankton and Chl-a for reasonable sinking depth in floating cage. Furthermore, we analyzed the fluctuation of the phytoplankton including harmful dinoflagellates occurring in Yokgido for 6 years. Total cell density showed a significant monthly variation and the flora was predominated with diatoms. Gymnodinium sp. occurred 19 times, the greatest number of occurrence in all kinds of dinoflagellates during summer. In particular, the total number of occurrence at C. polykrikoides was 8, and harmful dinoflagellates such as Karenia brevis/Fibrcapsa japonica occurred. The relationship between Chl-a concentration/total cell number and sunset/sunrise was significant and reasonable sinking depth in floating cage was found to be at least 3m from the water surface, which was associated with massive fish kills caused by C. polykrikoides.

• Journal of the Korean Professional Engineers Association
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• v.17 no.4
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• pp.8-14
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• 1984

In this part of the studies on dielectric dehydration of foamed fish-starch paste, quality stability and shelflife of the product of which the preparation formula and processing conditions were described in the previous report (Lee et at., 1982) were determined by means of accelerated reaction test. The product was stored for 50 days under the conditions of temperatures at 35, 45, and 55$^{\circ}C$ in steady state and various water activities of 0.44, 0.52, 0.65, and 0.75, respectively. The loss of available lysine, the extent of TBA value, and the development of browning during the storage were measured and reaction kinetically analysed to assess quality stability and shelf-life of the product for the storage at room temperature of 25$^{\circ}C$. The extent of browning was accelerated with the increase of water activity and temperature marking the time to reach a limit of color and flavor deterioration, or to reach brown color density of 0.17 O.D./g at 420nm, 106 days at a$\_$w/=0.44, 35$^{\circ}C$, and 41 days at aw=0.65, 55$^{\circ}C$. These reaction rates resulted in a prediction of shelf-life, 130 to 110 days in the storage at au=0.44 to 0.75, 25$^{\circ}C$. The quality limit assessed by TBA values and sensory evaluation of rancidity was 87 days at a$\_$w/=0.44, 35$^{\circ}C$, and 30 days at aw=0.73, 55$^{\circ}C$ which gave a predicted shelf-life, 128 to 113 days at a$\_$w/=0.44 to 0.75, 25$^{\circ}C$ storage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.437-443
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• 2018

This study investigates the effect of the mixing elements on the pressure loss and mixing performance in line mixer. The high density ozone water devices mixed with gas and liquid are used in various fields such as sterilizing of group feeding facilities and water quality management at a fish farm. Due to the decrease in rainfall due to climate change, pasteurization of drinking water from ground water and surface water is extremely important. Therefore, it is intended to develop a line-mixed gas liquid mixer with a small amount of space. In this study, the effects of the number of static mixers and the types and the number of the orifice used in line mixer on the volume fraction and the pressure loss were studied by CFD simulation. The pressure drops of line mixer with orifice which curved vanes were attached to were down to more than 50 percent of that of line mixer with static mixer whereas the mixing performance of the former was similar to that of the latter.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.271-280
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• 2010

Vibrio alginolyticus, a Gram-negative marine bacterium, is one of the causative agents of fish vibriosis. Its virulence factors and pathogenesis mechanism are barely known, except for some extracellular products (ECPs) that are known to be regulated by quorum sensing system. Therefore, the present study used a microarray to analyze the transcription profiles of the wild-type V. alginolyticus and a deletion mutant of luxO, the pivotal regulator in Vibrio quorum sensing systems, which resulted in the identification of a putative virulence factor, MviN. Quantitative real-time reverse transcription PCR confirmed that the transcription of mviN was upregulated in the luxO mutant when compared with wild-type, and down regulated in a luxO-con complemented strain. Furthermore, Western blotting indicated that MviN was greatly induced during the late-exponential and stationary phases of growth, indicating that the expression of MviN was cell-density dependent and quorum sensing regulated in V. alginolyticus. Meanwhile, the mviN null mutant displayed a much slower growth rate than the wild type, signifying the essential role of MviN in V. alginolyticus. Western blotting also revealed that MviN was present as an extracellular protein in V. alginolyticus. When epithelioma papulosum cyprini (EPC) cells were treated with the ECPs of the mviN mutant, no cytotoxicity was observed, whereas EPC cells treated with the wild type exhibited pathological changes, which increased with the ECPs concentration and treatment time. Therefore, the results demonstrated that MviN is a LuxO-regulated ECPs component and involved in the pathogenicity of V. alginolyticus.

• Journal of Nutrition and Health
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• v.30 no.10
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• pp.1140-1152
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• 1997

Serum and liver lipid levels and fatty acid composition of liver phospolipids (PL) were investigated in 36 rats which consumed either one of five different dietary fats or a high carbohydrate diet for 4 weeks. As the sources of five dietary fats, concentrated cicosapentaenoic acid(EPA), fish oil (FO), perilla oil(PO), corn oil(CO) and beef tallow (BT) were provided to the rats. As a control group, cron starch (CS) replaced dietary fat. The FO group showed lower serum total cholesterol (TC), high density lipiprotein cholesterol(HDL-C) and serum PL levels than those of the CO group(p<0.05). There were no significant differences in serum TC and serum HDL-C levels between the polyunsatured fatty acid(PUFA) groups and the EPA, FO and PO groups. The CS group showed the highest level serum TC. Compared with the CS group, both the EPA and CO groups showed significantly lower atherogenic indices(AI). However, there were no significant differences in AI among different dietary fat groups. No significant differences in liver triglyceride (TG) , TC and PL levels were detected among the six experimental groups. Phosphatidylcholine(PC) and phosphatidylethanolamine(PE) composed 30-40% and 15-20% of total liver PL, respectively. The fatty acid composition of liver PC and PE reflected dietary fatty acid composition . Compared to the different dietary fat based diets used in our study, the high carbohydrate diet had the most adverse effects on serum lipid profiles. However, we can not conclude from this result that long chain n-3 PUFA diets such as the EPA and FO based diets have more beneficial effects on serum lipid profiles than n-6 PUFA diet such as the CO based diet or shorter chain n-3 PUFA diets like the PO based diet.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.1
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• pp.90-94
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• 2008

Growth and water quality in Japanese eel, Anguilla japonica ($6.0{\pm}0.9g$) fed extruded and paste type diets were compared for 8 weeks. Fish in the duplicate tanks were fed with one of three experimental diets: two different extruded pellet diets and one paste type diet. Six FRP tanks were used with stocking density of 3.6 kg per tank (3 m3). Restricted feeds (ca. 2% of body weight) were served twice daily. Weight gains were checked at the end of every two-week interval, and water qualities in terms of NH4-N and NO2-N were determined daily one hour after feeding in the morning. Water temperature, dissolved oxygen, and pH were constantly kept within the optimum range, while fifty percent of total water volume was changed daily. Eels fed the extruded pellet diets showed significantly better (P<0.05) growth performance than did eels fed the paste type diet. The amount of feed waste from the paste type diet was significantly greater than those from the extruded pellet diets (P<0.05). Ammonia (NH4-N) waste was significantly higher from the paste diet than from the extruded pellet diets (P<0.05). These results show that extruded pellet diets are better than the paste type diet for growth and water quality management in eel culture.